ok throughout the halo trilogy, there was strange songs that played when you reach a certain spot in the game, I'm not shure if anyone posted this, but if someone did tis topic will confirm thers. Ok the song is reportedly called "The Siege of Madrekel" from the Myth series. In Halo 1 you have to steal a Banchie on the level 'Assault on the control room. and when your close to the control room, dont get off the banchie youll fly upwards toward three platforms, land on the second platform, this is above were the control room is, then when you land on the 2nd platform you walk slowly toward the right side of the platform, then you tern left towards the edge,and when you at the edge you stop, and then in a few more seconds, the song will play.
in halo 2 its on Ivory Tower, neer a Gerage door.
in halo3 The Covenate- Rally point Bravo- you have to steal a banchie or fly the hornate, whichever is closer and fly it towards the citidel area towards the left platform thats part of the citidel. you land on it and you keep walking on it ontil it slopes upwards, keep going until you reach the spot that goes strait up. Wait a few seconds and you'll hear the song,
I hope I gave good instructions.